The present invention relates to a method of scanning aerofoil blades, and more particularly relates to a method of CT scanning a plurality of aerofoil blades.
Computed tomography (“CT”) is now a widely available technology, and it has been proposed previously to use the CT techniques for investigative work on the internal geometry of aerofoil blades, and in particular turbine blades for gas turbine engines.
Previously proposed methods for CT scanning turbine blades for gas turbine engines have all necessitated scanning a single blade at a time. This is mainly to the extremely high density of material used in the manufacture of most turbine blades (usually high density nickel super-alloys). The extremely high density of the turbine blade material has meant that scanning more than one blade at a time absorbs too much x-ray energy to provide sufficiently clear images of the blades' aerofoil sections for meaningful analysis. This previous requirement to scan each blade individually has thus precluded the use of CT scanning techniques to inspect the internal structure of a large number of blades as would be required, for example, for routine inspection in a production environment. CT scanning has therefore tended to be used on an ad hoc basis for the inspection of small numbers of turbine blades. A convenient and reliable way to scan a plurality of aerofoil blades would therefore offer significant advantages.